his pair of images provided by the web analytics firm Mezzobit shows a graphic representation of a mainstream news site, left, and a fringe news site, right. The square icons show the "root" of a page within the site, and the web of dots emanating from it shows the tags or vendors that are loaded on that page. Mezzobit has found that fringe news sites tend to be less sophisticated in their advertising, as shown by fewer branches emanating from the root. (Mezzobit via AP)

What distinguishes mainstream news sites from those devoted to fake news or other hyper-partisan takes on events? It's not just the stories they run, but also the way they use online technology that tracks readers and shows them ads, according to a new study by a web analytics firm.

In particular, the study—from the New York-based startup Mezzobit—showed that such fringe news sites are relatively unsophisticated in the way they make money from online ads, perhaps because many are shoestring operations that can easily cover their costs.

Stories shown on fake or fringe news sites are anything but mainstream. They run from made-up articles to pieces that start with a grain of truth but exaggerate it to fit highly opinionated perspectives. But they use the same underlying ad technology, which serves up ads intended to appeal to every individual who visits, as their mainstream counterparts—just in different, and sometimes revealing, ways.

For starters, fringe sites typically aren't as focused on using tools that maximize ad revenue by auctioning slots to the highest bidder, according to the Mezzobit study. Instead, they generally tap run-of-the-mill services from ad networks like those run by Google and Facebook.

One reason? Mainstream sites need to make a lot of money. After all, it's more expensive to fund actual journalism than to make things up from thin air. Fringe sites "can make money with just a small footprint," said David Carroll, professor of media design at the Parsons School of Design in New York. Carroll, who is not affiliated with Mezzobit, was given an overview of the report.

Mezzobit compared the underlying ad technology used at fringe and mainstream news sites the week of Dec. 5. It started with a list of fringe sites created by Jonathan Albright, a professor who studies data journalism at Elon University in North Carolina. Albright calls the fringe sites "hyper-biased" propaganda.

For a mainstream comparison, Mezzobit used a list from Amazon's Alexa that tracks the top news sites on the web. The list is comparable with other ranking systems such as comScore's.

To be sure, some of the differences in the ad-tech footprints of mainstream and fringe news sites are similar to what you'd expect to find from comparing any large companies to smaller rivals, said Joseph Galarneau, Mezzobit's CEO and co-founder.

"A lot of the fringe sites looked a lot more sparse," he said. They had fewer tracking cookies and fewer links to outside sites and content. As a result, they were also 8 percent faster to load than the mainstream sites.

Carroll said he was more troubled by the similarities between mainstream and fringe sites.

The study revealed that advertisers aren't shunning fringe news sites the way they avoid placing ads on sites that feature porn or gambling. And major ad networks appear to be letting advertisers place ads on fringe sites.

Although Google says it will prohibit its ads from being placed on "misrepresentative content," it doesn't explicitly single out "fake news" as part of this. Google also licenses its ad technology to advertisers it might not normally accept, indirectly profiting from such sites. Facebook has said that it bans fake news articles it knows about from its advertising network, but it doesn't do so for entire sites.

"This presents a really challenging problem to the industry and to advertisers," Carroll said. "The report shows plenty of exposure from Facebook and Google and the rest of the industry to this stuff."